Computer controlled focused ultrasound positioning system for sequential beam emitting to sonicate discrete and interleaved tissue locations

Abstract

A focused ultrasound system includes an ultrasound transducer configured to emit focused ultrasound energy toward a subject and a positioning system configured to position the ultrasound transducer to localize the focused ultrasound energy within a target location. The positioning system includes a drive apparatus to translate the ultrasound transducer along at least one axis of motion and a motor controller to control the drive apparatus. The focused ultrasound system also includes a control system connected to the motor controller that is programmed to receive imaging/location data from an imaging system, determine positional coordinates of the target location based on the imaging/location data, and register the positional coordinates of the target location with the positioning system. The positional coordinates are sent to the motor controller via an input signal to cause the motor controller to control the drive apparatus so as to translate the ultrasound transducer.

What is claimed is: 
     
       1. A focused ultrasound system for localizing a beam of focused ultrasound energy within a plurality of target locations in a subject, the focused ultrasound system comprising:
 an ultrasound transducer configured to emit a beam of focused ultrasound energy toward the subject; 
 a positioning system configured to position the ultrasound transducer to localize the beam of focused ultrasound energy within the plurality of target locations in the subject, the positioning system comprising:
 a drive apparatus including an actuator to cause translation of the ultrasound transducer along at least one axis of motion; and 
 one or more motor controllers configured to control the drive apparatus; and 
 
 a computer connected to each motor controller and to the ultrasound transducer, the computer programmed to:
 define a repetition period for emitting beams of focused ultrasound energy from the ultrasound transducer to the plurality of discrete target locations; 
 send control signals to each motor controller to control the drive apparatus to sequentially translate the ultrasound transducer to a series of transducer locations during each repetition period, such that at each transducer location, ultrasound energy emitted by the ultrasound transducer is focused to a respective discrete target location; and 
 control the ultrasound transducer to sequentially emit the beams of focused ultrasound energy during each repetition period, such that a beam of focused ultrasound energy is emitted at each transducer location, and such that each of the discrete target locations is sonicated during each repetition period according to an interleaved sonication pattern. 
 
 
     
     
       2. The focused ultrasound system of  claim 1  wherein the drive apparatus comprises a non-magnetic drive apparatus including:
 a first linear stage configured to adjust a position of the ultrasound transducer in a first horizontal direction; 
 a second linear stage configured to adjust a position of the ultrasound transducer in a second horizontal direction; 
 a third linear stage configured to adjust a position of the ultrasound transducer in a vertical direction; and 
 an ultrasonic motor corresponding to each of the first linear stage, the second linear stage, and the third linear stage, the ultrasonic motors configured to selectively translate the first linear stage, the second linear stage, and the third linear stage so as to position the ultrasound transducer to localize the beam of focused ultrasound energy within the target location in the subject. 
 
     
     
       3. The focused ultrasound system of  claim 2  wherein the first and second linear stages comprise linear ball slides and wherein the third linear stage comprises a rotary-type stage. 
     
     
       4. The focused ultrasound system of  claim 1  wherein the positioning system is configured to control positioning of the ultrasound transducer in increments at or below a resolution of the imaging or location data used to define the target location. 
     
     
       5. The focused ultrasound system of  claim 1  further comprising a water tank, wherein the ultrasound transducer is enclosed within the water tank, and the drive apparatus is located outside the water tank. 
     
     
       6. The focused ultrasound system of  claim 5  further comprising: 
       a plurality of rods configured to connect the ultrasound transducer to the drive apparatus, the plurality of rods entering at least one side of the water tank; and 
       a flexible bellows configured to maintain a watertight seal where the plurality of rods enter the at least one side of the water tank. 
     
     
       7. The focused ultrasound system of  claim 1  further comprising a water cone having a flexible membrane at a tip thereof positioned between the ultrasound transducer and the subject such that the beam of focused ultrasound energy is transmitted therethrough. 
     
     
       8. The focused ultrasound system of  claim 1  further comprising an optical encoder connected to the drive apparatus to measure the translation of the ultrasound transducer. 
     
     
       9. The focused ultrasound system of  claim 1  wherein the plurality of target locations were identified by way of an image acquired by an MR imaging system; and
 wherein the motor controller is configured to generate a sinusoidal voltage output to drive the drive apparatus, the sinusoidal voltage output having a frequency below an operational frequency of the MR imaging system so as to minimize interference therebetween during imaging. 
 
     
     
       10. The focused ultrasound system of  claim 1  wherein the computer is programmed to:
 monitor and analyze at least one sonication related parameter during exposure of the subject to the beam of focused ultrasound energy; and 
 based on the at least one sonication related parameter, control emission of the beams of focused ultrasound energy from the ultrasound transducer or display a value of the at least one sonication related parameter to an operator. 
 
     
     
       11. The focused ultrasound system of  claim 10  further comprising a secondary transducer configured to measure acoustic emissions related to gas bubble activity within the subject during exposure to the beam of focused ultrasound energy; and
 wherein the computer is programmed to control emission of the beams of focused ultrasound energy from the ultrasound transducer or display a value of the acoustic emissions to an operator based on the measured acoustic emissions. 
 
     
     
       12. The focused ultrasound system of  claim 10  further comprising a secondary transducer configured to transmit ultrasound pulses and receive ultrasound echoes for ultrasound imaging of the target location; and
 wherein the computer is programmed to control emission of the beams of focused ultrasound energy from the ultrasound transducer or display a value of the ultrasound echoes to an operator based on the received ultrasound echoes. 
 
     
     
       13. The focused ultrasound system of  claim 10  further comprising a means for measuring forward and reflected electrical power transmitted to the ultrasound transducer, the means for measuring forward and reflected electrical power configured to have a temporal resolution sufficient for characterizing individual RF pulses; and
 wherein the computer is programmed to control emission of the beams of focused ultrasound energy from the ultrasound transducer or display a value of the forward and reflected electrical power to an operator based on the measured forward and reflected electrical power transmitted to the ultrasound transducer. 
 
     
     
       14. The focused ultrasound system of  claim 10  further comprising a fiber-optic temperature sensor configured to measure a temperature of the subject; and
 wherein the computer is programmed to control emission of the beams of focused ultrasound energy from the ultrasound transducer or display a value of the temperature to an operator based on the measured temperature of the subject. 
 
     
     
       15. A system for localizing a beam of focused ultrasound energy within a plurality of target points in a subject, the system comprising:
 a first non-magnetic actuator to adjust a position of a first linear stage in a first horizontal direction; 
 a second non-magnetic actuator to adjust a position of a second linear stage in a second horizontal direction; and 
 a third non-magnetic actuator to adjust a position of a third linear stage in a vertical direction; 
 one or more motor controllers configured to selectively drive the first, second, and third non-magnetic actuators so as adjust the linear stages, thereby translating an ultrasound transducer to a desired location in three dimensions relative to the plurality of discrete target points; and 
 a computer connected to each motor controller and to an ultrasound transducer, the computer programmed to:
 define a repetition period for emitting beams of focused ultrasound energy from the ultrasound transducer to the plurality of discrete target points; and 
 send control signals to each motor controller to control the first, second, and third non-magnetic actuators to sequentially translate the ultrasound transducer to desired locations in three dimensions during each repetition period, such that at each transducer location, ultrasound energy emitted by the ultrasound transducer is directed to a respective discrete target location; and 
 control the ultrasound transducer to sequentially emit the beams of focused ultrasound energy during each repetition period, such that a beam of focused ultrasound energy is emitted at each transducer location, and such that each of the plurality of discrete target points is sonicated during each repetition period according to an interleaved sonication pattern. 
 
 
     
     
       16. The system of  claim 15  wherein each of the first, second, and third non-magnetic actuators comprises an ultrasonic piezoelectric actuator. 
     
     
       17. The system of  claim 15  wherein the first, second, and third non-magnetic actuator actuators are configured to adjust the linear stages with a precision of between 50 microns and 0.3 millimeters. 
     
     
       18. The system of  claim 15  further comprising: a water tank configured to receive the ultrasound transducer therein, the ultrasound transducer being enclosed in the water tank and the first, second, and third non-magnetic actuators and the linear stages being located outside the water tank;
 a plurality of rods configured to connect the ultrasound transducer to the linear stages and the rotary stage, the plurality of rods entering at least one side of the water tank; and 
 a flexible bellows configured to maintain a watertight seal where the plurality of rods enter the at least one side of the water tank. 
 
     
     
       19. The system of  claim 15  further comprising an optical encoder coupled to each of the linear stages to generate feedback on a measured movement of the ultrasound transducer. 
     
     
       20. The system of  claim 15  wherein the computer is further programmed to send control signals to the one or more motor controllers to drive at least one of the first, second, and third actuators to translate the ultrasound transducer during acquisition of imaging data by the medical imaging system. 
     
     
       21. A focused ultrasound system for localizing a beam of focused ultrasound energy within a plurality of target locations in a subject, the focused ultrasound system comprising:
 an ultrasound transducer configured to emit a beam of focused ultrasound energy toward a subject; 
 a three-axis positioning system configured to position the ultrasound transducer in three dimensions, the three-axis positioning system comprising; a drive apparatus including an actuator to cause translation of the ultrasound transducer in three dimensions and one or more motor controllers configured to control the drive apparatus; and 
 a computer connected to each motor controller and to the ultrasound transducer, the computer programmed to:
 define a repetition period for emitting beams of focused ultrasound energy from the ultrasound transducer to the plurality of discrete target locations; 
 send control signals to each motor controller to control the drive apparatus to sequentially translate the ultrasound transducer to a series of transducer locations during each repetition period, such that at each transducer location, ultrasound energy emitted by the ultrasound transducer is directed to a respective discrete target location; and 
 control the ultrasound transducer to sequentially emit the beams of focused ultrasound energy during each repetition period, such that a beam of focused ultrasound energy is emitted at each transducer location, and such that each of the discrete target locations is sonicated during each repetition period according to an interleaved sonication pattern. 
 
 
     
     
       22. The focused ultrasound system of  claim 21  wherein the drive apparatus comprises a non-magnetic drive apparatus including:
 a first linear stage configured to adjust a position of the ultrasound transducer in a first horizontal direction; 
 a second linear stage configured to adjust a position of the ultrasound transducer in a second horizontal direction; 
 a rotary stage configured to adjust a position of the ultrasound transducer in a vertical direction; and 
 an ultrasonic motor corresponding to each of the first linear stage, the second linear stage, and the rotary stage, the ultrasonic motors configured to selectively translate the first linear stage, the second linear stage, and the rotary stage so as to position the ultrasound transducer to the at least one desired location. 
 
     
     
       23. The focused ultrasound system of  claim 21  wherein the computer is programmed to send motor control signals to activate the three-axis positioning system to translate the ultrasound transducer to the at least one desired location concurrently with acquisition of additional imaging data. 
     
     
       24. The focused ultrasound system of  claim 1  wherein the plurality of discrete target locations are positioned along a linear scan path, with the computer being programmed to cause the motor controller to control the drive apparatus to sequentially translate the ultrasound transducer to each discrete target location along the linear scan path such that the beams of focused ultrasound energy are localized within each of the discrete target locations along the linear scan path within each repetition period.